A Phase 1 Study to Evaluate the Safety, Tolerability and Pharmacokinetics of BCX4430

Inclusion Criteria: 1. Weight ≥ 50 kg (110 lbs) and ≤ 100 kg (220 lbs) 2. Body mass index (BMI) of 19-32 kg/m2 3. Willing to abstain from alcohol consumption for a period of 2 days prior to and during the study 4. Sexually active women of child bearing potential and sexually active men must utilize 2 highly effective contraceptive methods 5. Abstain from caffeinated beverages 6. Normal vital signs at rest 7. Ability to provide written informed consent Exclusion Criteria: 1. Subjects who are study site employees, or immediate family members of a study site or sponsor employee 2. Participation in a clinical research study within the previous 90 days 3. Any medical condition or medical history that, in the opinion of the investigator or sponsor, would interfere with the subject's ability to participate in the study or increase the risk of participation for that subject 4. Any screening laboratory test with an abnormal result that is grade 1 (mild) or greater 5. Abnormal ECG (defined as any screening or baseline QTc\>450 msec, PR \> 200 msec, or ventricular and/or atrial premature contractions that are more frequent than occasional, and/or as couplets or higher in grouping 6. An abnormal cardiovascular exam including a confirmed elevated blood pressure at screening (systolic greater than 140, diastolic greater than 90) after 5 minutes of supine rest, tachycardia \>100 bpm after 5 minutes of supine rest 7. Family or personal history of sudden death or QT prolongation 8. Use of prescription, over-the-counter (OTC) medications or herbal supplements, with the exception of acetaminophen and non-oral hormonal contraception, for a period of 7 days prior to and during the study 9. Inadequate muscle mass to receive IM injections 10. History of alcohol or drug abuse within the previous year, or current evidence of substance dependence or abuse 11. Current smokers or history of smoking within the last 12 months 12. Serious adverse reaction or serious hypersensitivity to any drug 13. Presence or history of clinically significant allergy requiring treatment, as judged by the investigator. Hayfever is allowed unless it is active 14. Donation or loss of greater than 400 mL of blood within the previous 3 months 15. Positive serology for hepatitis B surface antigen, hepatitis C antibody, or human immunodeficiency virus (HIV) type 1 16. Pregnant or nursing females 17. Male subjects with pregnant female partners